Method for producing a stamped substrate

ABSTRACT

A method and apparatus is provided for forming a power distribution system during a punching operation. A planar member of conductive material is located proximate to the substrate upon which the power distribution system is to be formed. A punch used to form the conductors from the planar member and deposit the conductors on the substrate. The action of the punch causes mechanical interference between the conductor and the substrate thereby securing the conductor to the substrate.

This is a continuation of U.S. patent application Ser No. 923,807 filedOct. 27, 1986, now abandoned.

BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates to the field of stamped substrates, and inparticular to the fabrication and attachment of conductors to substrateswhich may then be used in a power distribution system for circuit boardassemblies.

Appliances and other articles often use power distribution systems todeliver electrical power from power cords to the electrical componentsin the appliance. To accommodate the relatively high wattage which thepower distribution systems carry, the conductors in such powerdistribution systems have to be relatively large. Because of theconductor, size, assembly of such power distribution systems are oftenperformed manually.

There are several problems associated with manual assembly of powerdistribution systems. First, the cost of manually assembling the powerdistribution systems is often as much as 20-30% of the total assemblycost. In addition, manual assembly of power distribution systemsoccasionally results in premature failure due to open or intermittentconnections formed during assembly. For these reasons, it is desirableto automate as much of the assembly as possible.

One technique for automatic assembly of circuit board patterns is shownin U.S. Pat. No. 2,971,249. This patent discloses a three-step processfor depositing conductive patterns on substrates. A die-blanking pressis used to form and deposit a conductive pattern on a base material. Thedie-blanking operation is followed by a punching operation and a moldingoperation. The conductive pattern is bonded by an adhesive materialdeposited on the substrate or by using a separate molding operation.

Accordingly, it is the primary object of the present invention toprovide an improved power distribution system for use in appliances andother articles which does not require adhesive bonding or molding tosecure conductors to substrates.

In addition, it is a further object of the present invention to providea method for automatically assembling power distribution systems.

Another object of the present invention is to provide a powerdistribution system that is reliable, relatively inexpensive, and simpleto fabricate.

In general, the method of assembling a power distribution systemaccording to the present invention comprises: locating a planar memberproximate to the structure upon which the power distribution system isto be assembled. A punch is then used to punch a planar member so as toform and attach the conductors of the power distribution system to thesubstrate by creating mechanical interference between the conductor andthe substrate.

Additional objects and advantages of the present invention will becomeapparent upon reading the following detailed description of thepreferred embodiments which make reference to the accompanying drawingsin which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the apparatus for forming stamped substratesaccording to the present invention;

FIG. 2 is a cross-sectional view of the apparatus for forming stampedsubstrates taken through line 2-2 of FIG. 1;

FIGS. 3(a)-(l) illustrates various manners in which a conductor can besecured to a substrate using the apparatus shown in FIG. 1;

FIGS. 4(a)-(c) illustrate the manner in which vertically orientedconductor projections can be formed and secured using the apparatusshown in FIG. 1;

FIG. 5 illustrates a multilayer circuit board which may be formed usingthe apparatus shown in FIG. 1;

FIGS. 6(a)-(d) illustrate the manner in which a component with an axiallead is connected to a stamped substrate formed by using the apparatusshown in FIG. 1;

FIGS. 7(a)-(e) illustrate the manner in which the apparatus shown inFIG. 1 may be used to form switches on a stamped substrate;

FIG. 8 illustrates a heat sink which is formed by the apparatus shown inFIG. 1;

FIG. 9(a) and (b) is a molded cordset connector block which may beformed in part by the apparatus shown in FIG. 1; and

FIG. 10(a) and (b) illustrates a power distribution system which isformed using the apparatus shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, an apparatus 10 is shown for depositing theconductors 12 on the substrates 14 according to the present invention.The substrates 14 may be formed from molded plastic, stamped fiberboard,or sheet plastic extrusion, though it is to be understood othermaterials may be used. The apparatus 10 receives a carrier strip 16 fromwhich the conductors 12 are formed. The carrier strip 16 is a planarmember fabricated from copper, brass, bronze, aluminum, or othersuitable materials.

To form the conductors 12 from the carrier strip 16, the apparatus 10includes a punch 18 which sequentially blanks the carrier strip 16thereby forming the conductor 12. Once the conductors 12 are formed bythe punch 18 during the blanking operation, the punch 18 deposits theconductors 12 onto the substrates 14. The conductors 12 are secured tothe substrate 14 by mechanical interference between the conductors 12and the substrates 14 in the manner described below. To support thepunch 18, the apparatus 10 includes a punch plate 20 and a die plate 22.The punch plate 20 is vertically disposed over the die plate 22 and isconnected by a plurality of posts 24. The posts 24 insure that thegeometric relationship between the punch plate 20 and the die plate 22is maintained. The die plate 22 floats on the posts 24 so that the dieplate 22 will not interfere with the projections 28 on the substrate 14during the indexing operation described below. To permit separation ofthe punch plate 20 from the die plate 22 during the upward stroke of thepunch 18, a plurality of springs 30 are provided. The springs 30 areused to bias the position of the punch plate 20 in a direction opposingthe die plate 22.

To deliver substrates 14 to the apparatus 10, an indexing mechanism 32is provided. The indexing mechanism 32 includes a base portion 34 and amovable member 36 with a plurality of lateral members 38. The indexingmechanism 32 sequentially delivers the substrate 14 to a position belowthe punch 18 by movement of the lateral members 38. After the punch 18blanks and deposits the conductors 12 on a particular substrate 14, thelateral member 38 moves a new substrate 14 into position underneath thepunch 18.

Several means for securing conductors 12 to the substrates 14 may beused. As shown in FIG. 3(a), the substrate 14 has a projection 40 whichis initially able to pass through an aperture in the conductor 12. Afterthe conductor 12 has been deposited on to the substrate 14 by a firstportion 42 of the punch 18, a second portion 44 of the punch 18 deformsthe projection 40 into a bead. The mechanical interference between theprojection 40 and the conductor 12 prevents the removal of the conductor12 from the substrate 14. In FIG. 3(b), the substrate 14 includes adepressed area 46 having a centrally located projection 40. To securethe conductor 12, the punch 18 deforms the projection 40 causing theprojection 40 to form a bead within the depressed area 46. Themechanical interference between the projection 40 and the conductor 12secures the conductor 12 to the substrate 14. By causing the projection40 to deform in this manner, the possibility that the projection 40 willinterfere with subsequent operations is minimized as the projection 40is located below the surface of the conductor 12.

Another means for securing the conductor 12 to the substrate 14 is shownin FIG. 3(c). After the conductor 12 is blanked as described above, thepunch 18 forces a portion 48 of the conductor 12 into the substrate 14.The material from which the substrate 14 is made then flows into theregion of the substrate 14 which is lanced, thereby securing theconductor 12 to the substrate 14. In FIG. 3(d), the punch 18 forces aportion 50 of the conductor 12 through an aperture 52 in the substrate14. Then the end of the portion 50 is then deformed as shown in FIG.3(e). In FIG. 3(f), the punch 18 is used to force a portion 54 of theconductor through an aperture 56 in the substrate 14. A roll set 58 isthen used to deform a region 60 of the portion 54 of the conductor 12 soas to secure the conductor 12 to the substrate 14. A similar means forsecuring the conductor 12 to the substrate 14 is shown in FIG. 3(g), inwhich the punch 18 forces a portion 61 of the conductor 12 through anaperture 62 in the substrate. The roll set 64 is then used to deform aregion 66 of the portion 61 of the conductor 12 to secure the conductor12 to the substrate 14.

Further means for securing the conductor 12 to a substrate 14 is shownin FIG. 3(h)-3(i). The substrate 14 is formed with a plurality of ribs68 which are able to receive the conductor 12. The conductor 12 isblanked from the carrier strip 16 and then deposited on the substrate 14between the ribs 68. A second punch 70 is then used to cold stake theribs 68. The mechanical interference between the ribs and the conductor12 thereby secures the conductor 12 to the substrate 14.

Additional means for securing the conductor 12 to the substrate 14 isshown in FIGS. 3(k)-3(l). In FIG. 3(k), the carrier strip 16 contains alance 72 which is able to be inserted into an aperture 74 in thesubstrate 14 during blanking. As the tip of the lance 72 reaches themovable member 36 during insertion, the edges of the lance 72 are forcedagainst the sides of the aperture 74, thereby mechanically securing theconductor 12 to the substrate 14. As shown in FIG. 3(l), the carrierstrip 16 contains a finger trapping lance 76 on the conductor 12. Thefinger trapping lance 76 is forced into the aperture 78 in the substrate14 so as to mechanically interfere with the substrate 14. While severalmeans for forming and securing the conductor 12 to the substrate 14 bymechanical interference are shown, other suitable techniques may beused. With respect to the formation of the apertures and lances, U.S.Pat. No. 2,971,249 illustrates the initial formation of various shapedcomponents before being secured to a base member as discussed above.

The apparatus 10 may be used to form and attach vertical conductorprojections to the substrate 14. As shown in FIG. 4(a), a conductor 12having a projection 80 is formed during the blanking operation. Theprojection 80 is then secured to the substrate 14 in the manner asdiscussed above. The apparatus 10 may also be used to form the conductor12 having the projections 80 in the manner shown in FIG. 4(b), in whicha form punch 86 is displaced vertically through an aperture 88 in thesubstrate 14 to cause the projection 80 to form against the punch 18.Alternatively, the punch 18 may force the projection 80 of the conductor12 through an aperture 92 in the substrate 14 as shown in FIG. 4(c).While several means for forming and securing vertical conductorprojections to substrates have been described above, it will beunderstood that other suitable means may also be used.

The apparatus 10 may also be used to form multilayer circuit boards. Asshown in FIG. 5, a substrate 94 is provided to which a first conductorlayer 96 is attached. An insulator layer 98 having a plurality ofapertures 100 is then secured to the conductor layer 96, upon which asecond conductor layer 102 is attached. The second conductive layer 102has a plurality of projections 104 which are able to extend through theapertures 100 in the insulator layer 98 and electrically communicatewith the first conductor layer 96. Accordingly, electrical power may bedelivered from the first conductor layer 96 to the second conductivelayer 102 through the projections 104.

The apparatus 10 may also be used to form and secure component terminalsto the substrates 14 as shown in FIG. 6(a)-(d). A component terminal 106is blanked to include a groove 108 for accommodating a lead 110 from acomponent 112. The component terminal 116 is then secured to thesubstrate 14 by mechanical interference in the manner described above.The component terminals 116 may be used for securing a wire 114 betweentwo portions 116 and 118 of an electrical assembly 120 as shown in FIG.6(b). The component terminals 106 may also be used for mechanicalsurface mounting an electrical component 122 as shown in FIGS. 6(c), inwhich the lead 124 from a component 122 passes through an aperture 126in the substrate 14 in which a portion 128 of the component terminal 106is disposed. The end of the lead 124 is then bent to physically securethe component 122 to the substrate 14 as well as to provide foradditional electrical connection. The substrate 14 may also includeprojections 130 which further secure the component 122 to the substrateas shown in FIG. 6(d).

The apparatus 10 can also be used to form a variety of switches 132 asshown in FIGS. 7(a)-(e). In FIG. 7(a), two stationary contacts 134 and136 are formed and secured to a substrate 14 by mechanical interferencein the manner described above. An actuator 138 is provided whichmechanically communicates with a movable contact 140. The movablecontact 140 is biased in a direction toward the stationary contact 134by a spring 142. When the actuator 138 is laterally moved, the movablecontact 140 mechanically communicates with both of the stationarycontacts 134 and 136 thereby providing electrical communicationtherebetween. In FIG. 7(b), two conductors 144 and 146 are secured tothe substrate by mechanical interference in the manner described above.The conductors 144 and 146 are vertically displaced to provide a gaptherebetween. An actuator 148 may be used to close the gap between theconductors 144 and 146 permitting electrical communication therebetween.In FIG. 7(c), a deformed portion of the conductor 150 is disposed in anaperture 152 in the substrate 14. The conductors 150 and 154 can then belocated close to the surface of the substrate 14 thereby minimizing thevertical space occupied by the switch 132. In FIG. 7(d), a firstconductor 156 includes a first portion 158 which is elevated from thesecond conductor 160. The actuator 148 may then be used to close theelectrical circuit by depressing the deformed portion 158 on to theconductor 160. In FIG. 7(e), the two conductors 164 and 166 are securedin the manner described above. The portions 168 and 170 of theconductors 164 and 166 are bent by 90 degrees with respect to the unbentportion. Contact between the conductors 164 and 166 is then made byallowing the actuator 148 to force the bent portion 168 of the conductor164 against the bent portion 170 of the conductor 166.

The apparatus 10 may also be used to form a heat sink 174 as shown inFIG. 8, in which a conductor 176 having a projection 178 is depositedand secured on the substrate 14 by mechanical interference in the mannerdescribed above. The electronic module 180 is then secured to theconductor 176 through a thermally conducted adhesive causing heat fromthe electric module 180 to flow into the conductor 176. The heatgenerated by the electronic module 180 then flows into the conductor 176and is dissipated into the environment through the projection 178. Inthis embodiment, the substrate 14 may be used to distribute power to theelectronic module 180 through a second conductor 182 and the stakeheader 184.

The apparatus 10 may also be used in the formation of a terminal block186 as shown in FIGS. 9(a) and (b). The substrate 14 is formed havingthe retaining projections 188. The two conductors 190 and 192 are thenformed and deposited on the substrate 14 in the manner described above.Two die cast retainers 194 and 196 are then inserted into the substrate14 and are held in place by the retaining projections 188. The leads 198from the cordset may then be inserted into the apertures 200 of the diecast retainers 194 and 196, whereupon the screws 202 are used to securethe leads 198 of the cordset. After the screws 202 have been tightened,the wires 204 of the cordset are disposed against the retainingprojections 188.

The apparatus 10 may also be used to secure power cords to electricalunits in the manner as shown in FIGS. 10(a) and (b). The power cord 206includes a strain relief portion 208 which mates with the housing 210 ofthe unit 212. The cord 206 further includes two leads 214 and 216 whichare secured to a substrate 14 by molded conductor retainers 218 and 220in the substrate 14. Attached to the unit 212 are two conductors 222 and224 having conductor terminals 226 and 228 formed and secured in themanner described above. The conductors 222 and 224 act as a bus todistribute current to various components in the unit 212. Alternatively,the conductor 222 and 224 may electrically communicate with the barrelterminals 226 and 228 which allow for direct insertion of the leads 214and 216 as shown in FIG. 10(b).

While the above description constitutes the preferred embodiment of theinvention, it would be appreciated that the invention is susceptible tomodification, variation, and change without departing from the properscope of a fair meaning of the accompanying claims.

What is claimed is:
 1. A method for attaching a select portion of aplanar member to a substrate, said planar member having first and secondsurfaces, said first surface comprising a plurality of lances projectingbelow said planar member substantially normal thereto, said selectedportion having a first interengaging member comprising at least one ofsaid lances, said substrate having a second interengaging membercomprising an aperture, said method comprising the steps of:locatingsaid planar member proximate to said substrate such that said one lanceis substantially perpendicular to said substrate and at a position abovesaid aperture; disposing a die between said first surface of said planarmember and said substrate; disposing a punch proximate to said secondsurface of said planar member; and displacing said punch in a downwarddirection to separate said selected portion from said planar member,said step of displacing said punch in a downward direction operable tosecure said selected portion to said substrate by inserting said lanceinto said aperture thereby causing mechanical interference between saidlance and said aperture, said step of displacing said punch in adownward direction operable to form said selected portion and securesaid selected portion to said substrate in a single downward stroke ofsaid punch.
 2. The method of claim 1, wherein said second interengagingmember comprises a projection, said step of displacing said punch in adownward direction operable to cause deformation of said projectionthereby securing said selected portion to said substrate.
 3. The methodof claim 1, wherein said step of displacing said punch in a downwarddirection includes the step of embedding said first interengaging memberinto said substrate.
 4. The method of claim 1, wherein said step ofdisplacing said punch in a downward direction includes the additionalstep of deforming said one lance of said selected portion after said onelance is inserted through said aperture in said substrate.
 5. The methodof claim 4, wherein a portion of said one lance projects through saidaperture in said substrate when said one lance is inserted in saidaperture.
 6. The method of claim 5, wherein said portion of said onelance engages a roll set and is deformed so as to permit said portion ofsaid one lance to engage said substrate.
 7. The method of claim 1,wherein said second interengaging member comprises at least one rib,said step of displacing said punch in a downward direction operable tocause mechanical interference between said rib and said firstinterengaging member.
 8. The method of claim 1, wherein said step ofdisplacing said punch in a downward direction includes the additionalstep of forcing a portion of said lance against a fixture supportingsaid substrate thereby causing said lance to deform.
 9. A method forforming and securing an electrical conductor to a substrate, saidelectrical conductor able to be formed from a planar member ofconductive material having first and second surfaces, said first surfacecomprising a plurality of lances projecting below said planar membersubstantially normal thereto, said planar member further having a firstinterengaging member comprising at least one of said lances, saidsubstrate having a second interengaging member comprising an aperture,said method comprising the steps of:locating said planar memberproximate to said substrate such that said one lance is substantiallyperpendicular to said aperture and at a position above said aperture;disposing a die between said first surface of said planar member andsaid substrate; disposing a punch proximate to said second surface ofsaid planar member; and with a single downstroke of a punch, formingsaid electrical conductor from said planar member by punching saidplanar member with said punch, and securing said electrical conductor tosaid substrate by inserting said lance into said aperture therebycausing mechanical interference between said lance and said aperture,said step of forming said electrical conductor operable to form saidelectrical conductor and secure said electrical conductor to saidsubstrate without substantial upward movement of said punch.
 10. Themethod of claim 9, wherein said second interengaging member comprises aprojection, said step of securing said electrical conductor to saidsubstrate operable to cause deformation of said projection therebysecuring said electrical conductor to said substrate.
 11. The method ofclaim 9, wherein said step of securing said electrical conductorincludes the step of embedding said first interengaging member into saidsubstrate.
 12. The method of claim 9, wherein said step of securing saidelectrical conductor includes the additional step of deforming a regionof said one lance after said region is inserted through said aperture insaid substrate.
 13. The method of claim 12, wherein a portion of saidone lance projects through said aperture in said substrate when said onelance is inserted in said aperture.
 14. The method of claim 9, whereinsaid second interengaging member comprises at least one rib, said stepof securing said electrical conductor operable to cause mechanicalinterference between said first interengaging member and said rib. 15.The method of claim 9, wherein said step of displacing said punch in adownward direction includes the additional step of forcing a portion ofsaid lance against a fixture supporting said substrate thereby causingsaid lance to deform.
 16. The method of claim 15, wherein said portionof said one lance engages a roll set and is deformed so as to permitsaid portion of said one lance to engage said substrate.
 17. A methodfor forming an electrical component mounting from a planar member andsecuring said electrical component mounting to a substrate, said planarmember having first and second surfaces, said first surface of saidplanar member having a plurality of lances projecting below said planarmember substantially normal thereto, said electrical component mountingcomprising at least one of said lances, said substrate including anaperture, said method comprising the steps of:locating said planarmember proximate to said substrate such that said one lance issubstantially perpendicular to said aperture; disposing a die betweensaid first surface of said planar member and said substrate; with asingle downstroke of a punch, forming an electrical component mountingfrom said planar member by punching said planar member by a punchingelement, and securing said electrical component mounting to saidsubstrate by inserting said lance into said aperture thereby causingmechanical interference between said lance and said aperture, said stepof forming said electrical component mounting operable to form saidelectrical component mounting and secure said electrical componentmounting to said substrate without substantial upward movement of saidpunch.
 18. The method of claim 17, wherein said step of displacing saidpunch in a downward direction includes the additional step of forcing aportion of said lance against a fixture supporting said substratethereby causing said lance to deform.
 19. The method of claim 17,wherein a portion of said one lance projects through said aperture insaid substrate when said one lance is inserted in said aperture.
 20. Themethod of claim 19, wherein said portion of said one lance engages aroll set and is deformed so as to permit said portion of said one lanceto engage said substrate.
 21. The method of claim 20, wherein said stepof displacing said punch in a downward direction includes the additionalstep of forcing a portion of said lance against a fixture supportingsaid substrate thereby causing said lance to deform.